How Often Should LEV Be Tested?

A lot of businesses believe LEV systems need a Thorough Examination & Test (TExT) every 14 months.

It’s one of the most commonly repeated “facts” in health & safety.

And in some cases, it’s true.

But in many others, relying on the 14-month rule can leave you non-compliant, exposed, and with a false sense of security – especially when your LEV system falls under Schedule 4 of COSHH 2002, where more frequent testing is required.

If you provide extraction for welding fume, wood dust, isocyanates, metalworking fluids or other higher-risk processes, then “every 14 months” is almost certainly wrong.

Below is a simple guide to when LEV needs testing, why the 14-month rule is often misused, and what the law actually requires.

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Why People Think LEV Needs Testing Every 14 Months

COSHH Regulation 9 states that LEV must be examined and tested:

“…at least once every 14 months unless more frequent intervals are specified in Schedule 4.”

This line gets repeated endlessly in workplaces, often becoming:

“LEV is every 14 months. End of story.”

But that’s not what COSHH says.

COSHH actually says:

• 14 months is the maximum interval, not the default.
• Some systems legally require shorter intervals.
• Risk-based increases in frequency may be necessary where exposure potential is high.

So if your system doesn’t fall under the 14-month category, you’re already non-compliant even if you think you’re doing the right thing.

What Schedule 4 of COSHH Actually Says (In Plain English)

Schedule 4 lists specific LEV processes and substances that must be tested more often than 14 months.

Here are the most common examples:

Every 6 Months – Mandatory

These LEV systems must legally be tested at least once every 6 months:

✔ Wood dust extraction

Wood dust is a known carcinogen and respiratory sensitiser, hence the stricter interval.

✔ Welding fume extraction

Including MIG, TIG, MMA, fume arms, on-torch extraction and plasma cutting.

✔ Metalworking fluids (MWF) LEV

High risk of respiratory illness, mist exposure and bacterial contamination.

✔ Spray booths and isocyanate processes

Includes automotive refinishing, 2K paints and any process producing isocyanate mist.

✔ Abrasive blasting

Both free-standing and cabinet blasting systems.

✔ Certain dusts and fumes listed under Schedule 4 hazardous substances

If your LEV falls under any of these, a 14-month test isn’t legally acceptable.

Every Month – In Some High-Risk Scenarios

This is the part most businesses overlook.

Schedule 4 includes processes requiring monthly examination, usually where:

• LEV performance can degrade very quickly
• The consequences of failure are severe
• Exposure potential is high or continuous

Examples include:

• Electrolytic chromium processes
• Certain high-toxicity dusts and vapours
• Processes generating highly corrosive or rapidly clogging contaminants

These are less common but still present in UK manufacturing.

When 14 Months Is Acceptable

The 14-month interval generally applies to:

• Basic benchtop LEV systems
• Low-risk dust extraction
• Simple point-of-use extraction in non-hazardous processes
• Systems not specified in Schedule 4
• Situations where risk assessments show low degradation and low exposure potential

However – and this is key:

14 months is the absolute longest allowable interval.

Not the default, not the recommendation.

If the system’s performance can degrade sooner, testing must be more frequent.

Common Myths That Lead to LEV Failures

Myth 1: “It’s the same LEV system, so the interval is always the same.”

Wrong.

The process determines the frequency – not the equipment type.

Myth 2: “Our last provider said it’s always 14 months.”

Also wrong.

Plenty of providers don’t follow Schedule 4 correctly.

Myth 3: “We’ve never had an issue, so 14 months is fine.”

HSE doesn’t accept “we’ve always done it this way” as a defence.

Myth 4: “We can switch between substances without changing the interval.”

The interval must follow the highest-risk material being extracted.

Myth 5: “Our in-house checks mean we can extend the interval.”

LEV thorough examinations are a legal requirement, not a risk-based optional control.

What Can Happen If You Test LEV Too Infrequently

Inaccurate or outdated LEV testing exposes a business to:

• Workers inhaling hazardous dusts, fumes or mist
• Uncontrolled exposure to carcinogens and sensitisers
• Invalidated COSHH assessments
• Enforcement notices
• Compensation claims
• Invalid insurance in the event of occupational disease
• Failed audit outcomes

Most exposure-related enforcement cases start with one finding:

“LEV was not examined at the required intervals.”

How to Set the Correct LEV Test Frequency

A competent LEV engineer should:

• Identify the process
• Identify the contaminants
• Reference Schedule 4
• Review deterioration potential
• Review hours of use
• Assess risk of blockage, corrosion or filter wear
• Recommend the correct interval (not just the convenient one)

Velocity Safety does this automatically as part of every LEV Thorough Examination & Test.

A Quick Reference Guide

These are the test intervals that actually appear in COSHH Schedule 4 (translated into plain English):

Process / Contaminant	Legal Test Frequency
Wood dust	Every 6 months
Welding fume	Every 6 months
Isocyanates / Spray booths	Every 6 months
Metalworking fluids	Every 6 months
Abrasive blasting	Every 6 months
Electrolytic chromium	Every month
Other Schedule 4 processes	1–6 months depending on risk
Low-risk processes not in Schedule 4	Up to 14 months

If your LEV system handles any of the substances above, the interval is already set for you.

If it isn’t listed, then you fall into risk-based territory – and that’s where many businesses accidentally drift into non-compliance by defaulting to 14 months.

The safest approach?

Match the interval to the process risk, not the convenience of the calendar.

Why Velocity Safety Gets LEV Testing Right

Instead of simply recording airflow numbers and handing over a certificate, Velocity Safety looks at how the system actually performs in the real world. That means:

• Confirming the correct test interval under COSHH and Schedule 4
• Using calibrated, traceable instruments
• Checking whether controls are still adequate for the task
• Reporting defects clearly, with no sugar-coating
• Advising if the interval needs tightening due to process risk

Compliance isn’t a box-tick – it’s making sure the LEV is genuinely protecting people.